Nickel(II) Complex of N4 Schiff Base Ligand as a Building Block for a Conducting Metallopolymer with Multiple Redox States

Metal–ligand interactions in monomeric and polymeric transition metal complexes of Schiff base ligands largely define their functional properties and perspective applications. In this study, redox behavior of a nickel(II) N₄-anilinosalen complex, [NiAmben] (where H₂Amben = N,N′-bis(o-aminobenzylidene)ethylenediamine) was studied by cyclic voltammetry in solvents of different Lewis basicity. A poly-[NiAmben] film electrochemically synthesized from a 1,2-dichloroethane-based electrolyte was investigated by a combination of cyclic voltammetry, electrochemical quartz crystal microbalance, in situ UV-Vis spectroelectrochemistry, and in situ conductance measurements between −0.9 and 1.3 V vs. Ag/Ag⁺. The polymer displayed multistep redox processes involving reversible transfer of the total of ca. 1.6 electrons per repeat unit, electrical conductivity over a wide potential range, and multiple color changes in correlation with electrochemical processes. Performance advantages of poly-[NiAmben] over its nickel(II) N₂O₂ Schiff base analogue were identified and related to the increased number of accessible redox states in the polymer due to the higher extent of electronic communication between metal ions and ligand segments in the nickel(II) N₄-anilinosalen system. The obtained results suggest that electrosynthesized poly-[NiAmben] films may be viable candidates for energy storage and saving applications.     

Structure and properties of blends containing ethylene-methacrylate copolymers

The preparation, melting point, degree of crystallinity, mechanical properties, and morphology of a family of blends composed of a transition-metal-neutralized carboxylate semicrystalline ionomer (metal-neutralized ethylene-methacrylate copolymer) and an amorphous copolymer (styrene-4-vinyl pyridine copolymer) are described. These polymeric materials contain low levels (≤ 10.0 mol %) of interacting groups which are capable of forming interpolymeric complexes. These interactions are best described as transition metal-pyridine coordination complexes. A general characteristic of these blend systems is that the mechanical properties and morphology are directly influenced by the nature of the counterion and the specific composition ratio of amorphous to semicrystalline component. A nontransition metal counterion (sodium) is weakly interacting at best, while a transition metal counterion (zinc) is strongly interacting. Morphological studies (polarized-light microscopy and small-angle light-scattering measurements) confirm that the glassy component, if nonassociating, resides primarily in the interspherulite region, while the associating species will behave in a similar manner only after the stoichiometric ratio is reached. The morphology directly influences the stress-strain behavior of these blends. It is noteworthy that the spherulite size remains unchanged with nonassociating blends while a 50% reduction is noted in the associating blends. Thermal and wide-angle x-ray scattering measurements confirm the lamellar structure is unaffected by these associations. © 1992 John Wiley & Sons, Inc.     

温和条件下氧分子的活化和活性氧种的反应

固氧问题和氮、二氧化碳的固定同样都是人类认识自然、利用自然的重要课题。近年来,人们开始对氧在温和条件下的活化和反应问题发生极大兴趣,这是和下面二个待开发的领域受到普遍注意分不开的。     

ANiN(A=Li,Na,Mg,Ca)的结构、热力学、弹性和电子性质的第一性原理研究

三元过渡金属氮化物ANiN(A=Li,Na,Mg,Ca)是潜在的可充放电池的电极材料.物理性质,比如热稳定性、电子能隙以及弹性稳定性等,对于这些材料的电池应用都是非常重要的.本文使用第一原理方法,对比研究了 ANiN这些材料的结构、动力学、弹性和电子结构性质.对状态方程和声子谱的计算被用来确定体系的稳定结构.对最稳定结...     

ChemInform Abstract: Syntheses and Properties of a Family of New Compounds RE3Sb3Co2O14 (RE: La,Pr, Nd,Sm—Ho) with an Ordered Pyrochlore Structure.

As an example of the isostructural Ln₃Sb₃Co₂O₁₄ (Ln: La, Pr, Nd, Sm—Ho) series with an ordered pyrochlore structure, the La variant is prepared by a citrate complex method employing stoichiometric amounts of La(NO₃)₃, Co(NO₃)₂, and Sb tartrate together with citric acid with a metal/citrate molar ratio of 1:2 (1.     

Oligo‐Ortho‐Chloroazomethinephenol and its Metal Complexes: Synthesis,Characterization, Antimicrobial and Thermal Properties

The new Schiff base oligomer (oligo‐ortho‐chloroazomethinephenol) was synthesized by the condensation of ortho‐chloroaniline with oligosalicylaldehyde (OSA). Oligomer‐metal complexes of oligo‐ortho‐chloroazomethinephenol (OKAP) with Cu(II), Zn(II) and Co(II) were synthesized. The properties of OKAP and oligomer‐metal complexes were studied by elemental, UV‐Vis, ¹H‐NMR, FT‐IR, magnetic susceptibility analyses. The number average molecular weight and mass average molecular weight OKAP were found to be 1494 g · mol^?1 and 5418 g · mol^?1, respectively. Elemental analyses of oligomer‐metal complexes suggest that the ratio of metal to oligomer is 1∶2. The results indicate that the OKAP coordinate through azomethine nitrogen and phenolic oxygen to the metal ions. Antimicrobial activity of OKAP was tested against S. cerevisiae, B. subtilis, E. coli, K. pneumoniae, M. luteus and S. aureus. The thermal stabilities of the OKAP and oligomer‐metal complexes were compared by thermogravimetric (TG) analyses. According to TG, OKAP, and oligomer‐metal complexes were stable against temperature and thermooxidative decomposition. The weight losses of OKAP and oligomer‐metal complexes were found to be at 400 and 800°C at 20.2 and 50.0 (OKAP), 17.1 and 41.1 (Cu(II)), 13.4 and 38.5 (Zn(II)), 18.3 and 68.2 (Co(II)), %, respectively. Based on half degradation temperature (T_50%) parameters, Cu(II) and Zn(II) complexes were more resistant than the OKAP and Co(II) complex.     

Site‐Resolved Two‐Step Relaxation Process in an Asymmetric Dy2 Single‐Molecule Magnet

Elaborate chemical design is of utmost importance in order to slow down the relaxation dynamics in single‐molecule magnets (SMMs) and hence improve their potential applications. Much interest was devoted to the study of distinct relaxation processes related to the different crystal fields of crystallographically independent lanthanide ions. However, the assignment of the relaxation processes to specific metal sites remains a challenging task. To address this challenge, a new asymmetric Dy₂ SMM displaying a well‐separated two‐step relaxation process with the anisotropic centers in fine‐tuned local environments was elaborately designed. For the first time a one‐to‐one relationship between the metal sites and the relaxation processes was evidenced. This work sheds light on complex multiple relaxation and may direct the rational design of lanthanide SMMs with enhanced magnetic properties.     

ChemInform Abstract: Synthesis and Crystal Structure of the A6B5O18 Perovskite-Like Compounds.

Single phase Ba₅KNb₅O₁₈ (I) is prepared by solid state reaction of Ba₅Nb₄O₁₅ and KNbO₃ (1370 K, 2 h), while Sr₆Nb₄SnO₁₈ (II) results from calcination of the coprecipitated metal hydroxycarbonates (1570 K, 2 h).     

银纳米棒光学性质的离散偶极近似计算

The optical properties of metal nanoparticles are quite different from those of the bulk materials mainly due to the collective oscillations of their conduction electrons known as the surface plasmon resonance（SPR）,which is strongly dependent on the particle shape and size,and the dielectric properties of the local environment where the nanoparticles are embedded in. Based on the discrete dipole approximation（DDA）method,we studied the optical properties of silver nanorods with different aspect ratios in some special dielectric environment including air,water,acetone,methylene chloride and pyridine. The DDA simulation of the ultraviolet-visible（UV-Vis）extinction spectra of silver nanorods with varying aspect ratios shows the plasmons absorption splits into two bands corresponding to the oscillation of the free electrons along and perpendicular to the long axis of the rods. The transverse mode shows almost a fixed resonance at about 350 nm while the resonance of the longitudinal mode is red-shifted and strongly depends on the aspect ratio of the nanorods. An empirical formula was given to predict the peak position of the longitudinal palsmon band of the silver nanorods with different aspect ratios in the air. The calculation result also shows the maximum of the longitudinal plasmon band of a silver nanorod with a fixed aspect ratio depends on the medium dielectric constant in a linear way. The TEM image and corresponding UV-Vis extinction spectrum of silver nanosphere and nanorods synthesized by our lab are in good agreement with the DDA simulation results.     

Assembly of π‐Conjugated Phosphole Azahelicene Derivatives into Chiral Coordination Complexes: An Experimental and Theoretical Study

Aza[n]helicene phosphole derivatives have been prepared from aza[n]helicene diynes by the Fagan–Nugent route. Their photophysical properties (UV/Vis absorption and emission behavior) have been evaluated. Their behavior as P,N chelates towards coordination to Pd^II and Cu^I has been investigated: metal–bis(aza[n]helicene phosphole) assemblies are formed by a highly stereoselective coordination process, as demonstrated by X‐ray crystallography. An aza[6]helicene phosphole bearing an enantiopure helicene part has been obtained, which allows the preparation of enantiopure Pd^II and Cu^I complexes with original topologies and high molar rotation (MR) and circular dichroism (CD). The structure–property relationship established from the experimental data has been studied in detail by theoretical studies (TDDFT calculations of UV/Vis, CD, and MR). Aza[n]helicene phosphole derivatives show π conjugation extended over the entire molecule, and its influence on the MR of aza[6]helicene phosphole 5 c has been demonstrated. Finally, it has been shown that the nature of the metal (coordination geometry and electronic interaction) can have a great impact on the amplitude of the chiroptical properties in metal–bis(aza[n]helicene phosphole) assemblies.     

In situ Synthesis of Metal Nanoparticle Embedded Free Standing Multifunctional PDMS Films

We demonstrate a simple one‐step method for synthesizing noble metal nanoparticle embedded free standing polydimethylsiloxane (PDMS) composite films. The process involves preparing a homogenous mixture of metal salt (silver, gold and platinum), silicone elastomer and the curing agent (hardener) followed by curing. During the curing process, the hardener crosslinks the elastomer and simultaneously reduces the metal salt to form nanoparticles. This in situ method avoids the use of any external reducing agent/stabilizing agent and leads to a uniform distribution of nanoparticles in the PDMS matrix. The films were characterized using UV‐Vis spectroscopy, transmission electron microscopy and X‐ray photoemission spectroscopy. The nanoparticle‐PDMS films have a higher Young's modulus than pure PDMS films and also show enhanced antibacterial properties. The metal nanoparticle‐PDMS films could be used for a number of applications such as for catalysis, optical and biomedical devices and gas separation membranes.

     

Organometallic based biologically active compounds: synthesis of mono‐ and di‐ethanolamine derived ferrocenes with antibacterial,antifungal and cytotoxic properties

Condensation reactions of 1,1′‐diacetylferrocene with ethanolamine were studied. The obtained compounds were further investigated for their ligation and biological properties with Co(II), Cu(II), Ni(II) and Zn(II) metal ions. The synthesized compounds were characterized by their physical, spectral and analytical properties and screened for their antibacterial properties against pathogenic bacterial strains, e.g. Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus and Salmonella typhi and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata using the agar‐well diffusion method. All the compounds have shown good antibacterial and antifungal activity, which increased on coordination with the metal ions, thus introducing a potential class of organometallic‐based antibacterial and antifungal agents. Brine shrimp bioassay was also carried out for in vitro cytotoxic properties against Artemia salina. Copyright © 2007 John Wiley & Sons, Ltd.     

稀土元素表面处理对玻璃纤维填充金属—塑料多层复合材料冲击磨损性能的影响

金属 塑料多层复合材料由钢背、烧结多孔青铜中间层和聚四氟乙烯 (ＰＴＦＥ)与填料混合物组成的表层复合而成 ,具有金属和塑料原有的优良性能 ,如高的机械性能、低的热膨胀系数和低的摩擦系数、良好的导热性和优异的减磨性[1～ 3 ] 。众所周知 ,玻璃纤维可用来提高ＰＴＦＥ复合材料的力学性能[4～ 6 ] 。纤维与基体之间的界面结合力起着控制聚合物复合材料力学性能的重要作用 ,并主要受纤维表面处理的影响[7～ 9] 。Ｗａｔａｎａｂｅ[10 ] 认为只填充玻璃纤维的ＰＴＦＥ复合材料在水中的磨损大于其它复合材料 ,玻璃纤维易受磨损且细碎的玻…     

Thermal and ion-exchange studies on chelating terpolymer resins derived from o cresol urea formaldehyde

Terpolymers prepared by condensation of o cresol and urea with formaldehyde in presence of acid catalyst (2 M HCl) proved to be selective chelating ion exchange resins for certain metal ions. The molecular weights of the synthesised terpolymers were determined by GPC Technique. TGA analysis was employed to study the thermal stability and the kinetic data like activation energy of the terpolymer resins. Chelation ion exchange properties of these terpolymers were studied for Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Pb²⁺ and Cd²⁺ ions. A batch equilibrium method was employed in the study of the selectivity of metal ion uptake involving the measurements of distribution of a given metal ion between the polymer samples. The study was carried out over a wide pH range and in media of various ionic strengths.     

Metal Redox Processes for the Controlled Synthesis of Metal Alloy Nanoparticles

Nanocrystalline metals have received widespread interest and found various applications owing to their magnetic and catalytic properties and in energy‐related fields. A flexible approach for the growth of nanoalloys with controlled properties and well‐defined structures on the atomic scale is thus greatly desired. A new synthetic method that avoids incompatible reduction potentials and rates would be critical to grow metal nanostructures with high purities and the desired stoichiometries. A metal‐redox strategy that employs spontaneous oxidation/reduction reactions to grow nanocrystalline alloys using molecular‐scale zerovalent metal precursors is now described. The selection of suitable zerovalent metal species allows for thermodynamic control of the compositional stoichiometry during the temperature‐dependent formation of the metal alloy nanoparticles. A practical and scalable strategy for nanoalloy growth that can potentially produce key metal components of superior metallurgical quality for catalytic and magnetic systems has thus been developed.     

Structural,mechanical, electronic,and thermodynamic properties of pure tungsten metal under different pressures: A first-principles study

The structural, mechanical, electronic, and thermodynamic properties of pure W metal under different pressures have been investigated using the first-principles method. Our calculated structural parameters are in good agreement with experimental and previous theoretical results. The obtained elastic constants show that pure W metal is mechanically stable. Elastic properties such as the bulk modulus (B), shear modulus (G), Young's modulus (E), Poisson's ratio (ν), Cauchy pressure (C′), and anisotropy coefficients (A) are calculated by the Voigt-Reuss-Hill method. The results show that the pressure can improve the strength of pure tungsten and has little effect on the ductility. In addition, the total density of states as a function of pressure is analyzed. Thermodynamic properties such as the Debye temperature, phonon dispersion spectrum, free energy, entropy, enthalpy, and heat capacity are also discussed.     

识别过渡金属离子的1,8-萘二甲酰亚胺多胺衍生物荧光传感器的研究

A series of fluorescent chemosensors 1-3 were synthesized to detect transition metal ions. At the room temperature, fluorescence intensities of these chemosensors in acetonitrile without transition metal ions were found to be very weak, due to the process of the e±cient intramolecular photoinduced electron transfer (PET). However, after addition of the transition metal ions, the chemosensor 1-3 exhibits obvious fluorescence enhancement. Moreover, the intensity of the fluorescence emission of chemosensors increases significantly in the presence of Zn2+ and Cd2+. The fluorescent chemosensors with different polyamine as receptors show diverse a±nity abilities to the transition metal ions and signal the receptor-metal ion interaction by the intensity change of fluorescence emission.     

ChemInform Abstract: EPR Spectra of Coinage Metal Atoms Trapped in Evaporated Alkali Metal Chloride Matrices at Low Temperatures.

The EPR spectra of Cu, Ag, and Au atoms, trapped directly in vapor-deposited alkali metal chlorides LiCl, NaCl, KCl, and CsCl using the rotating-cryostat technique, show much lower hyperfine interactions than gas-phase metal atoms or atoms in alkali metal chloride single crystals (prepared from the ions in cationic substitutional sites by electron capture).     

Toxicological Effects of Metal Nanoparticles Employed in Biomedicine: Biocompatibility,Clinical Trials,and Future Perspective

Metal nanoparticles play a crucial role in the medical industry due to its desirable properties such as antimicrobial activity, anti-cancer property, and its application in disease diagnostics. These properties enable the nanoparticles to be used as efficient medical devices for various treatments as well as drug delivery systems. Despite all the positives, metal nanoparticles are known for causing toxicity in the living system. The toxicological effects of metal nanoparticles are due to their size, surface*e coating, and the dose administered. Therefore, it is important to study the toxic effects of these nanoparticles before they are used as medical devices for various treatments. This review focuses on the five major metal nanoparticles used in the medical field, namely; silver, gold, iron oxide, zinc oxide, and titanium dioxide nanoparticles. The non-exhaustive review consists of an introduction to the toxicological effects of these nanoparticles, the biocompatibility, and the current and future clinical perspective on metal nanoparticles.     

Experimental Investigation of the Biofunctional Properties of Nickel–Titanium Alloys Depending on the Type of Production

Nickel–titanium alloys used in dentistry have a variety of mechanical, chemical, and biofunctional properties that are dependent on the manufacturing process. The aim of this study was to compare the mechanical and biofunctional performances of a nickel–titanium alloy produced by the continuous casting method (NiTi-2) with commercial nitinol (NiTi-1) manufactured by the classical process, i.e., from remelting in a vacuum furnace with electro-resistive heating and final casting into ingots. The chemical composition of the tested samples was analyzed using an energy dispersive X-ray analysis (EDX) and X-ray fluorescence (XRF). Electron backscatter diffraction (EBSD) quantitative microstructural analysis was performed to determine phase distribution in the samples. As part of the mechanical properties, the hardness on the surface of samples was measured with the static Vickers method. The release of metal ions (Ni, Ti) in artificial saliva (pH 6.5) and lactic acid (pH 2.3) was measured using a static immersion test. Finally, the resulting corrosion layer was revealed by means of a scanning electron microscope (SEM), which allows the detection and direct measurement of the formatted oxide layer thickness. To assess the biocompatibility of the tested nickel–titanium alloy samples, an MTT test of fibroblast cellular proliferation on direct contact with the samples was performed. The obtained data were analyzed with the IBM SPSS Statistics v22 software. EDX and XRF analyses showed a higher presence of Ni in the NiTi-2 sample. The EBSD analysis detected an additional NiTi₂-cubic phase in the NiTi-2 microstructure. Additionally, in the NiTi-2 higher hardness was measured. An immersion test performed in artificial saliva after 7 days did not induce significant ion release in either group of samples (NiTi-1 and NiTi-2). The acidic environment significantly increased the release of toxic ions in both types of samples. However, Ni ion release was two times lower, and Ti ion release was three times lower from NiTi-2 than from NiTi-1. Comparison of the cells’ mitochondrial activity between the NiTi-1 and NiTi-2 groups did not show a statistically significant difference. In conclusion, we obtained an alloy of small diameter with an appropriate microstructure and better response compared to classic NiTi material. Thus, it appears from the present study that the continuous cast technology offers new possibilities for the production of NiTi material for usage in dentistry.